The Promise of Power
by ToraKU
Summary: One day when Yukio is out on a mission Amaimon shows up and offers to train Rin. Rin refuses, but when something happens will he accept this offer? What happens when he begins to see a different side of Amaimon? What will the others say about all of this? Amaimon x Rin, Yaoi, don't like don't read. Rating may go up for later chapters. Read and Review.
1. Prologue

Hello everyone. Welcome to this story. It's been awhile since I've posted anything. I recently got into this pairing so I hope you all enjoy it. :) Please review this I love getting feedback. Now, onto the story!

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Rin sat at his desk in his room all alone, trying to read his book for class. Yukio had been sent out on a mission and would be gone for a day or two so he had left them enough homework to make up for him not being there.

Rin groaned, dropping the book onto the floor. "Why couldn't he give us something interesting to do for once?" He mumbled, staring up at the ceiling. "This isn't going to help me become stronger."

"You're right. It won't help you become stronger," a voice said from the other side of the room.

Rin had been tipping his chair back when he heard the voice. It startled him and caused him to fall back and hit his head on the hard wood floor. He saw stars for second but quickly recovered. "Ow," he said as he got up, rubbing the back of his head. He looked over at the source of the voice and couldn't help the growl that escaped him. "How did you find me?"

Amaimon leaned against the door frame, the usual bored expression on his face. "It wasn't that hard. Brother refused to tell me so I tracked you. You have a very distinct scent, similar to father but at the same time very different," he explained. The tone in which he said this matched his expression.

"What do you want? Are you here to get your ass kicked again?" Rin asked, quickly making his way over to Kurikara, which lay on his bed.

Amaimon hid his smirk when he saw Rin go for the sword. This was exactly what he wanted. He waited until Rin was just about to grab the sword before he made his move.

Just as Rin's hand was about to close around the hilt of the sword, it was gone. He looked around the room, eyes wide and filled with confusion. Amaimon wasn't leaning against the door frame anymore. He on the other side of the room, holding the sword by it's sheath and tapping it against his shoulder as he looked at a picture on the wall of Rin and Yukio. "I never realized you were so sentimental Rin," he said.

Rin growled and took a defensive stand, getting ready to attack if need be. "Give it back," he demanded.

"I don't want to," Amaimon replied after a moment. Then he ripped the sword from it's sheath.

Blue flames engulfed Rin in and instant. His teeth and nails became sharper and his ears pointier. His tail had come out from under his shirt and was now swaying behind him.

Amaimon smirked. "Just like father. I don't get why you hide this form. It's so much better than that weak human form of yours"

Rin charged at him. "Give it back!" He shouted, swiping a clawed hand at the green haired demon.

Amaimon leaned back so far that he was staring straight up at the ceiling. Just as Rin's hand swiped where he had previously been he grabbed his wrist. Moving quickly, he twisted Rin's arm behind his back and pressed him up against the wall, dropping the sword in the process. "It's rude to attack someone out of the blue like that. Especially when they haven't even done anything wrong."

Rin thrashed, trying to get away, but he quickly gave that up when Amaimon twisted his arm just enough to cause a jolt of pain.

"You have no idea what you're capable of," Amaimon said, running a clawed finger along the back of Rin's neck. He pressed down just enough to break the skin. He smeared the blood that came out of the small cut with his finger. Then he brought that finger to his mouth and and licked it. "I could help you with that. With my help you could become so much stronger, you could reach your full potential."

"I don't want your help!" Rin spat, his flames flaring up.

Finally Amaimon let him go.

As soon as he was free, Rin shoved Amaimon aside and dove for the sword, but again he was too slow. Now on the ground, Rin looked up and saw Amaimon playing with the sword, running his claws along the blade. He laughed when he looked down and saw Rin on the floor. "With my help you could be this fast, but since you don't want my help I'll just leave. You're boring me anyways," Amaimon said as he returned the sword to it' sheath the blue flames that engulfed Rin disappeared instantly. He dropped the sword in front of the blue eyed boy and disappeared with a puff of green smoke.

Rin sighed and got up, grabbing kurikara and flopping down onto his bed, putting his sword next to him. Why was Amaimon offering to help him? Whatever the reason, there is no way in hell that he'd ever accept that offer.


	2. Chapter 1

Here's the next chapter. I can't believe I got it done so fast. I love writing this story. I really didn't want to end this chapter where I did but I just had to. It was the only way that made sense to end it. Anyways enjoy the chapter and please leave a review when you're done reading.

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"I heard about your little offer to Rin," Mephisto said. His head rested on the palm of his hand as he sat at his desk.

Amaimon sat on the windowsill behind his brother with his arms resting on his knees.

"Father hasn't given these orders. What are you up to?" The King of Time questioned. He spun around in his chair to face his younger brother.

"What makes you think I'm up to something? Father hasn't given these orders but do you hear him telling me to stop?" Amaimon said as he took the wrapper off a lollipop that he produced from his pocket and stuck it in his mouth.

Mephisto frowned. "I don't want you messing up all of my hard work. What happened to you following my orders? I said you could play again soon."

"Come on big brother you've been saying that for the past week. I'm bored," Amaimon complained, almost sounding like a spoiled child that didn't get what they want.

"Why don't you go site seeing then," Mephisto suggested, tapping his fingers on the arm of his chair.

"I've seen everything though. Rin is the only interesting thing around here and he just barely keeps me entertained," Amaimon replied, opening the window.

"Why have you taken such an interest in Rin all of a sudden?" Mephisto asked. He hadn't been this interested in Rin before.

"Why do I need a reason?" Amaimon asked as he stepped out onto the roof. "He said no anyways." With that said Amaimon closed the window and jumped across to the next roof.

Mephisto watched the green haired demon travel across roof tops until he was out of sight. He wasn't quite himself. He'd never turned down anything involving site seeing in Japan even if he had already seen it. As long as Rin didn't change his mind it would be fine.

Picking up the phone he quickly dialed a number and waited as the phone rang. Finally there was an answer and he spoke, "I need you to get here as soon as possible and keep a very close eye on Rin." He listened to the other person before responding, "I'll explain everything later, just hurry back." With that he hung up and looked back over in the direction Amaimon had gone. "Whatever you're up to brother… I will not let it ruin everything I have worked for."

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The next day when Rin woke up he noticed that Yukio's bag was on the floor next to his bed. He got up and looked at the bag in confusion. Yukio wasn't supposed to be back until tomorrow. Why was his stuff here? He shrugged figuring he'd find out later and went about his morning routine.

After showering and eating breakfast he grabbed his sword and grabbed the key that would take him to the exorcist cram school. Picking a random door in the hall he inserted the key in the lock and opened the door, stepping into the impressive hallway of the cram school. Ever since the postponing of his execution he had been put back into his usual courses. He was pretty far behind now since he had missed so much in those classes. He'd been more focused on gaining control of his flames while Yukio had attempted to drill in everything the cram school had been teaching but at a much faster pace. Now that he had control over his flames for the most part he was back to focusing on what everyone else was learning.

Just as he was about to open the door to the class room he was told to report to someone grabbed his arm. He turned and saw Amaimon standing there. "How the hell did you get here?!" He exclaimed, yanking his arms away and putting some distance between himself and the Earth King.

Amaimon watched Rin carefully, not showing any signs of hostility. "I stole the key from big brother," He said, holding up the key and the spinning it around his finger. "It was a lot easier than I thought it would be."

Rin glared at him. "Go away. I already told you I didn't want you're help," he snapped.

Amaimon frowns. "You're no fun anymore." With that he disappeared just like he had the day before. Rin stared at where the demon had been just a second ago, a confused expression on his face. Why was that guy so dead set on training him all of a sudden? The last couple times they had met they had been on opposite sides.

"Rin!" A female voice exclaimed.

Rin turned in the direction of the voice and saw Shiemi running over to him. He grinned when he saw her. "Hey Shiemi, how have you been, it's been awhile since I last talked to you."

Shiemi smiled at him, stopping when she was close enough to him to talk. "I've been doing great. What about you? How has your training been going?" She asked him.

"It's been going pretty well. I'm a lot better with my sword now that I've got my flames under control," Rin replied as he opened the door to the class room and let Shiemi go in first before following her inside.

"That's great!" Shiemi said as she and Rin took their seats at the desk in the front of the room. Rin looked around and saw that they were the only ones there. That was odd; usually he was one of the last people to arrive, not the first.

Just then everyone else began to file into the room.

"Hey Rin, long time no see," Shima said with a grin on his face as he walked past Where Rin was sitting and to his own seat.

"Yeah it's been awhile since I've seen everyone," Rin replied as Yukio quickly came into the room.

"You guys will have all the time in the world to talk later but right now there's a situation that we must go deal with immediately," Yukio said.

"What's going on?" Konekomaru asked.

"I'll explain on the way. Everyone follow me now," Yukio said and quickly excited the room with everyone following.

Rin walked alongside Bon and the others. "I wonder what's going on." He said.

"It can't be too bad if they want us there," Bon said.

Konekomaru and Shima nodded in agreement. "Yeah, they wouldn't throw us into anything too dangerous," Shima said. "It would be troublesome if they did."

Yukio lead everyone out of the school and quickly got them all onto a bus. As he got on the bus Rin saw Shura sitting in the front seat. Yukio quickly got everyone to sit down and the bus began to drive, going a little faster that a bus would usually go.

"Alright everyone, listen up!" Shura said loudly to get everyone's attention. All the whispers died down as everyone listened.

"This is not a test. Today we will be going out into the field to deal with a demon. Lately he's been tearing up an old mans farm. We are to stop this demon by any means necessary, is that clear?"

"Yes!" Everyone replied in unison.

"Alright get ready everyone we will be there in less than ten minutes," Yukio said.

During those ten minutes everyone got what they needed ready and discussed different ways to go about exorcising this demon. From the sound of it, it was going to be pretty easy.

As Rin talked with everyone else he noticed that bother Yukio and Shura were glancing over in his direction occasionally and they seemed to be discussing something. He frowned. They were acting like he had done something wrong. He didn't think he had done anything wrong, not from what he remembered anyways.

"Hey Rin, you there?" Bon asked Rin, waving a hand in front of his face.

Rin was pulled out of his thoughts and scratched the back of his head sheepishly. "Yeah sorry."

Bon sighed, "You haven't changed at all."

Rin glared at him, "What's that supposed to mean?!"

Just as Bon was about to respond they bus stopped and Yukio and Shura told everyone to get off and follow them.

The two exorcists lead the young exwires out into the field behind a small farm house. "We have a lot of land to cover so everyone get moving, split up and start searching." They said as they both went off in different directions. Everyone else followed suit and searched for any sign of a demon.

A couple hours later they all met up in the center of the field.

"I haven't seen any trace of a demon," Izumo said.

"Neither have I," Shima said.

Everyone else said the same. No one had come across even a trace of the demon that they had been told was here.

Suddenly the ground began to shake. Rin's eyes widened and his thoughts immediately went to Amaimon, thinking that this was his doing but that idea was quickly destroyed when a large demon burst up from underground a couple yards away from they group.

Shura and Yukio stared at it wide eyed. "Everyone stay back. Let us handle this!" Yukio exclaimed as both he and Shura began to attack the demon, but their attack did nothing and the demon threw them aside like there were nothing.

Rin and the rest of them stared in shock. Sure those two weren't at the top of the chain but they were both very strong. If Yukio and Shura were beaten so easily, they didn't stand a chance against that demon. Before they could do anything the demon attacked them, swinging a large hand at them one after another, knocking them all across the field into different spots until the last one standing there was Rin.

The demon had been so fast that Rin hadn't been able to draw his sword. For the first time in his life he was frozen in place, unable to move and even if he could he had no idea what he would do. Yeah he was strong, but Yukio and Shura were stronger than him. There was no way he'd be able to beat this thing. He was powerless. He couldn't even protect his own friends. Amaimon was right. He is weak.


	3. Chapter 2

I'm sorry this chapter is so short but this is just how it worked out. Anyways, enjoy the chapter and I'll try to get the next one up soon.

Rin X Amaimon

Amaimon hadn't been surprised that Rin had shot down his offer again. He had no reason to accept it after all. This however didn't mean he was going to give up. He wasn't even sure why he was doing this. He had no reason to go against Mephisto like this, but something made him want to do this.

He couldn't believe how oblivious Rin was though. That boy couldn't sense things at all. He hadn't really left he had just hidden himself and then followed Rin all the way to the farm. Now he stood atop a tree, watching everything unfold in front of him. He watched as the demon took out Rin's friends one by one, waiting to see what the half demon would do. He was surprised when Rin just stood there, staring at the demon and not doing anything. That was his cue to step in.

He jumped off the top of the tree and floated down in front of Rin. He looked up at the demon and said, "Go."

The demon obeyed immediately and dove underground, leaving the two demons alone. Once it was gone Amaimon looked around and sniffed the air. He could smell blood and quickly walked over to the source of it. It was that blond girl he had kidnapped that first time he had fought Rin. Her uniform was torn around the stomach area and drenched in blood. Amaimon crouched down next to her and tilted his head, looking at the wounds.

Rin ran over and attempted to shove Amaimon away but he wouldn't budge. "Get away from Shiemi!" He exclaimed. He didn't trust Amaimon one bit, especially not around Shiemi. Not after what happened the first time.

Amaimon looked over at Rin and then back at Shiemi. He took off one of his gloves and stuff it into a pocket on his jacket. Then he placed his hand on Shiemi's stomach and closed his eyes, concentrating.

Rin watch Amaimon and drew his sword, he was about to bring the sword down on Amaimon's head when he saw something he didn't think was possible. The wound's on Shiemi's stomach were healing. He couldn't believe his eyes. "You can heal?" He asked.

One of Amaimon's eyes opened and he glanced over at Rin. "I don't do this often." He replied.

"I didn't think demons were capable of healing," Rin said as he sheathed his sword.

"There's a lot of things you don't know about demons. You have no idea what we're capable of. You barely know what you're capable of," Amaimon said. Once the wounds on the girls stomach were gone, he removed his hand and wiped it off on the grass as best he could. "Disgusting," he said. He put his glove back on after he got off as much blood as he could.

Rin watched him. "Why the hell did you help me?" He asked the Earth King.

"You're weak," Amaimon said, not answering the question.

"That's why you helped?" Rin questioned, glaring at the other.  
"Big brother and everyone else are doing a terrible job training you," he said once again not answering the question.

Rin growled and grabbed Amaimon by his shirt collar. "Then you train me if you think you can do a better job!" He snapped.

Amaimon smirked, "You want me to train you now?"

Rin's face fell in realization of what he just said. Why the hell had he said that? He grit his teeth. Did he really want Amaimon to train him? He knew the other was right about him not knowing that much about demons, or at least he didn't know much about demons that were the children of Satan.

"Are you going to answer me or are you just going to stand there?" He asked the half demon. "You're starting to bore me."

"Train me," Rin finally said, tightening his grip on the others collar.

Amaimon smiled and began to laugh. "This is great! We'll start tomorrow!" He exclaimed. Then he disappeared in a puff of green smoke.

Rin was left there, staring at where the other had previously been. What the hell had he just agreed to?


	4. Chapter 3

Welcome back everyone. Here's the next chapter of The Promise of Power. I really hope you like it. I had a small bit of writers block. Mostly because I haven't been feeling well recently but I'm doing better now and I got through this chapter. Please and enjoy and leave a review. Reviews give me more motivation to write. Also thank you to everyone that has already reviewed the story. Anyways, onto the story!

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After Amaimon had left Rin's friends regained consciousness one by one.

"What happened to the demon?" Yukio questioned, looking at his brother who didn't have a single scratch on him.

"I defeated it," Rin lied.

Shiemi stared down at her torn and blood soaked clothes. "What happened to my stomach wound? I swore that demon had hurt me," she said. It was obvious she had been hurt but there wasn't a single trace of a wound.

"There wasn't anything there when I found you," Rin replied, lying once again.

Everyone looked at Rin unsure of what to say. How could he not know? He was the only one that had been conscious during the whole battle. They all decided that he was telling the truth.

Yukio went around checking to make sure that everyone was ok. Everyone except Shura was pretty much fine. Shura had sustained the worst injury. She had a sprained ankle. Of course she insisted that she was fine.

"See I'm fine. I can walk," she said, getting up and trying to take a step. As soon as she put weight on her ankle she bit her lip and fell to the ground. "I'm fine," she insisted. You could hear the pain in her voice.

Yukio sighed. "You are not fine. There is no way you can get back to the bus on your own." He looked at Rin as he said this and Rin groaned.

"Why do I have to carry her?" He asked.

"Out of all of us you're the strongest," Yukio replied. Everyone else nodded in agreement.

Rin grumbled but went over and knelt down, his back facing Shura. "Climb on."

Shura sighed and reluctantly climbing onto Rin's back, knowing that they weren't going to let her walk.

With that Rin stood up and they all went to go wait for the bus to come back and get them.

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After leaving, Amaimon had gone back to Gehenna to prepare for tomorrow. He hadn't told Rin what time but he knew that he didn't have classes tomorrow so he could just leave a note telling him where to meet him. It wouldn't be that hard. Neither Rin nor his brother had good sensing skills so he could go in and out without even being noticed. He was going to have to be careful though. If Mephisto found out he'd kill him. He knew he was messing with his elder brother's plans but he didn't care. He wasn't even sure what these plans were.

Now he wandered around the pits, listening to the screams of the souls being tortured.

Suddenly he sensed a presence beside him. "What is it Lucifer?" He asked.

"You're getting better," Lucifer commented. "Father wants to see you."

Amaimon narrowed his eyes at Lucifer's comment. Sure he wasn't as good as the rest of them at sensing thing but he wasn't that bad at it. He stopped walking when he heard that father actually wanted to see him. "Father wants to see me?" He questioned.

"Yes, and I'd hurry. You know he doesn't like to be kept waiting." Lucifer said and then walked off.

Amaimon turned and headed in the opposite direction to the throne room. He was curious as to why his father wanted to see him. He was one of the weakest demon kings so he didn't get as much attention as the others did. The lower down on the ladder you were the less attention you got.

When he got to the throne room it was completely empty. He frowned and looked around but still he saw no one. Where was father?

"I'm behind you son," A deep voice said from behind Amaimon.

Amaimon whirled around and saw his father. He towered over him. He was bigger than all of them. He was the king of the Gehenna after all.

"You're sensing skills are getting better but still not good enough."

"You asked for me father," Amaimon said respectfully. This was one of the few times that Amaimon was on his best behavior. He knew his place and now was not the time to be the way he usually is.

"Yes. I heard about your deal with Rin from Mephisto," Satan said, looking his son in the eyes. When he looked at you it was like he was looking deep into your soul. It was like his shockingly blue eyes saw through everything.

Amaimon sighed. Of course Mephisto told father. He's such a tattle tail.

"I do not want you anywhere near Rin. Mephisto is in charge of him. You're weaker than both of them. You couldn't possibly teach him anything."

Amaimon would have loved to punch his father in the face. That was if he could actually reach it. Then there's also the fact that he would be cast into the pits into an instant. Instead he just hid his anger and nodded. "Yes father. Is that all?"

"Yes that is all. You're dismissed," Satan replied, waving him off and walking to his throne.

Amaimon quickly left the room. A scowl appeared on his face as soon as he was out of the room and he began to chew on his thumb nail. This is going to be a problem.


	5. Chapter 4

Here's the next chapter. Sorry it took so long to post it. First I had the academic decathlon competition and then I had to finish a cosplay for Anime Boston along with other things. So basically I was super busy. By the way if you went to Anime Boston and saw someone dressed as Hades from Olympus Overdrive (a webcomic) that was me :) Anyways, enjoy the chapter.

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The next morning Rin was awoken by his alarm blaring. He fell out of his bed and ended up tangled up in his blankets on the floor. He heard laughing from across the room. He groaned and got up, untangling himself from the blankets and shutting off the alarm.

"You're way too easy to mess with. I got in here no problem once your brother was gone," Amaimon said from his seat on Yukio's bed.

Rin glared at him. "Just because I agreed to let you train me doesn't mean you can just show up whenever you want. I actually wanted to get some sleep today," he snapped at the older demon.

Amaimon tilted his head and looked at Rin. "I was bored, besides this means we have more time for training."

Rin ignored him and dug around his dresser draw, looking for something to wear. "Fine but we're getting food first," he said as he pulled out a plain black t-shirt and sweat pants. He needed to do laundry soon.

"What kind of food?" Amaimon asked curiously. He hoped it would be sweet.

"I don't know whatever I can find in the kitchen. I'm not feeding you though," Rin replied as he went into the bathroom to change.  
Amaimon frowned, "aw come on. I'm hungry."

"Well you should have thought about that before you came here and decided to mess with me," Rin shouted through the door.

A couple minutes later Rin came out of the bathroom his hair less of a mess and his tail now hidden. He ignored Amaimon and grabbed Kurikara, putting the sword in its bag and slinging it over his shoulder. Once that was done he left the room and headed down to the kitchen where he proceeded to look through the fridge and the cabinets.

Amaimon followed, pouting. He was hungry and he didn't have any candy or money on him. He watched Rin pull things out of the fridge and cabinets.

Rin began to cook, trying his best to ignore the pouting demon in the room. When the food was done he sat down and began to eat.

Amaimon watched his younger brother eat, practically drooling because of the smell. It smelt so good and he saw that there was extra food in the pan that Rin had used to cook. He looked at it for a minute and then decided to just go eat it.

"Hey I said I'm not feeding you!" Rin exclaimed when he saw Amaimon eating the extra food in the pan.

"I don't care. I'm hungry," he replied, sitting on the counter and eating.

Rin gritted his teeth and went back to eating. He decided that it probably wasn't a good idea to get between Amaimon and food.

Amaimon smirked, knowing that he had won and ate. It was delicious.

Once they were both done eating Amaimon set the pan aside and got down from his seat on the counter. He grabbed Rin by the arm and dragged him out of the dorm. "Come on. We need to get away from here before someone catches us." His main concern was making sure that Mephisto didn't find out.

Rin yanked his arm away from Amaimon and glared at him. "I don't need you dragging me across the city. That'll just get us spotted more easily."

Amaimon ignored him and continued to walk, taking a bit of a complicated route out of the city. This was the way he always went. It had the least amount of people. Exorcists barely ever came down this way.

Rin followed him, jumping in surprise when he hears someone call his name. He whirls around to see Shiemi running over to him.

Amaimon hears a voice call out Rin's name, quickly turning into a green hamster in a puff of green smoke. He hides behind Rin's leg.

"Rin! Have you seen Yukio?" Shiemi asks, stopping in front of him.

"No I haven't. Why? Didn't he say you should be resting today?" Rin asks, looking at her.

"Well he did… But I need to talk to him," She replies.

Rin shrugs, "Nope. I haven't seen him all day. I didn't even see a note in our room this morning."

"Oh, ok. Thanks anyways." Shiemi says. "Wait. Wasn't there someone with you when I was running over?" She asks in confusion.

"No there was no one with me. You must be seeing things. You really should go home and rest," Rin lies.

Shiemi frowns but nods. "Alright." With that she turns and walks away.

Once she's gone Amaimon changes back and begins walking again. "Come on we need to move faster," he says, sounding annoyed which wasn't something normal for him.

"What's your problem? It's only seven in the morning. We have plenty of time," Rin says, following behind the earth king.

"Just move faster," He snaps at the half demon.

Rin doesn't respond and does so. Something told him that today was going to be bad.


End file.
